Report on safety measures

Transcription

1 Report on safety measures for anchor handling vessels and mobile offshore units 10 february 2009 Report from the norwegian maritime directorate

2 1 ABBREVIATIONS Abbreviations regulations and guidelines Activities Regulations, the Regulations of 3 September 2001 No relating to conduct of activities in the petroleum activities Anchoring Regulations, the Regulations of 4 September 1987 No. 857 concerning anchoring/positioning systems on mobile offshore units Construction Regulations, the Regulations of 15 September 1992 No. 695 concerning the Construction of Passenger Ships, Cargo Ships and Barges Fire Regulations, the Framework regulations, the Immediate measures ISM Regulations, the ISM Code, the ISPS Code, the LSA Code, the Manning Regulations, the Marine Equipment Regulations, the Regulations of 22 June 1990 No. 536 concerning fire safety measures in ships to which the International Convention for the Safety of Life at Sea (SOLAS-74) applies Regulations of 31 August 2001 No relating to health, environment and safety in the petroleum activities Guidelines published by the Norwegian Maritime Directorate on 16 May 2007, as subsequently amended by RSV (Circular) Regulation of 14 March 2008 No. 306 concerning a Safety Management System for Norwegian ships and mobile offshore units International Safety Management Code International Ship and Port Facility Security Code International Life-Saving Appliance Code Regulations of 17 March 1987 No. 175 concerning the Manning of Norwegian ships Regulations of 29 December 1998 No concerning marine equipment (the Marine Equipment Regulations) Navigation Regulations, the Norwegian Maritime Code, the Regulation of 15 September 1992 No. 701 concerning Navigational Aids and Arrangements on the Bridge and in the Wheelhouse, and Communication Equipment in the Wheelhouse of Ships The Norwegian Maritime Code of 24 June 1994 No. 39 2

3 Notification and reporting Regulation, the NWEA guidelines Petroleum legislation, the Qualification Regulations, the Regulation of 27 June 2008 No. 744 concerning the notification and reporting of casualties and other incidents at sea Guidelines for the safe management of offshore supply and anchor handling operations NWEA (North West European Area) Acts relating to petroleum activities and Regulations and guidelines issued pursuant to these Regulation of 9 May 2003 No. 687 concerning Qualification requirements and certificate rights for personnel on board Norwegian ships, fishing vessels and mobile offshore units Radio Regulations, the Regulation of 17 December 2004 No concerning radiocommunication for cargo ships Rescue Regulations, the Regulation of 17 December 2004 No concerning life-saving appliances on cargo ships Rescue Regulations, the (passenger ships): Safety Measures Regulations, the Seaworthiness Act, the Ship Safety and Security Act, the: SOLAS STCW Convention, the STCW Code, the Watchkeeping Regulations, the Regulation of 11 October 2004 No concerning life-saving appliances on passenger ships Regulations of 15 June 1987 No. 507 concerning Safety Measures, etc. on Passenger Ships, Cargo Ships and Lighters Act of 9 June 1903 No. 7 relating to Public Control of the Seaworthiness of Ships, etc. Act of 16 February 2007 No. 9 relating to Ship Safety and Security International Convention for the Safety of Life At Sea, 1974 International Convention on Standards of Training, Certification and Watchkeeping for Seafarers, 1978 Seafarers Training, Certification and Watchkeeping Code Regulations of 27 April 1999 No. 537 concerning watchkeeping on passenger ships and cargo ships Working Environment Regulation, the Regulation of 1 January 2005 No. 8 concerning the working environment, health and safety of workers on board ship 3

4 Other abbreviations AHTS: AHT: BP: Commission: Anchor Handling, Tug and Supply Anchor Handling and Tug Bollard Pull The Commission of Inquiry into the loss of the Bourbon Dolphin on 12 April 2007 DNV: EPIRB: DP: GM: Det Norske Veritas Emergency Position Indicating Radio Beacon Dynamic Positioning The distance from the vessel s centre of gravity to the metacentre GZ curve: Curve for righting arm as function of heeling moment IACS: IMO: KG limit curve: NMD: OLF: POB list: PSV: RMP: S-VDR: VCG: International Association of Classification Societies Ltd. International Maritime Organization Maximum distance between keel (baseline) and centre of gravity to meet stability requirements for a given draught and trim Norwegian Maritime Directorate Norwegian Oil Industry Association Persons On Board list Platform Supply Vessel Rig Move Plan Simplified Voyage Data Recorder Vertical Centre of Gravity 4

5 Contents 1 ABBREVIATIONS SUMMARY INTRODUCTION Terms of reference More on the measures More on the Ship Safety and Security Act The Commission s commentaries to the NMD Follow-up of recommendations from the Commission STABILITY OF ANCHOR HANDLING VESSELS (13.3) Stability calculations (13.3.1) Problem as described in the Commission s report Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Stability booklet (13.3.2) Problem as described in the Commission s report Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Training/operations (13.3.3) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation DESIGN AND CERTIFICATION (13.4) The bollard pull certificate (13.4.1) Problem to be addressed as described by the Commission Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Requirements for the winch package (13.4.2) Problem as described by the Commission Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation

6 5.3 Certification of winch operator (13.4.3) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Direct emergency exit from the engine-room (13.4.4) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation EQUIPMENT (13.5) Liferafts (13.5.1) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Survival suits (13.5.2) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation EPIRB (13.5.3) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Voyage data recorder (VDR) (13.5.4) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation REQUIREMENTS FOR THE COMPANY S SAFETY MANAGEMENT (13.6) Vessel-specific anchor handling procedure (13.6.1) Problem as described by the Commission Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Overlap/familiarisation/handover (13.6.2) Problem as described by the Commission Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Identify need for qualifications (13.6.3)

7 7.3.1 Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation POB LISTS (13.7) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation PLANNING OF THE RIG MOVE (13.8) Problem as described by the Commission Recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation EXECUTION OF THE RIG MOVE (13.9) Start-up meeting and communication (13.9.1) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Tandem operations (13.9.2) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation Attention zones for running-out of anchors (13.9.3) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation The NMD s recommendation DUTY OF NOTIFICATION OF MARITIME ACCIDENTS OUTSIDE NORWEGIAN TERRITORY (13.10) Problem to be addressed and recommendation from the Commission Status of the regulatory system The NMD s evaluation OTHER MEASURES Stability instruments Status of the regulatory system The NMD s evaluation The NMD s recommendation OVERVIEW OF PROPOSALS FOR MEASURES

8 2 SUMMARY The proposed safety measures range from planning and training, via new requirements for stability, winches, voyage data recorders (VDRs), stability instruments, liferafts and EPIRBs to safety management actions. For the maritime activity, the measures cover requirements for mobile offshore units and vessels. In order to achieve a holistic approach to safety management, several of the measures should lead to changes in the Norwegian petroleum legislation. All together, the measures are expected to provide improved safety for anchor handling operations and the operation of anchor handling vessels. The focus on planning from a safety perspective, where risk assessment is central, and demands for closer cooperation between the parties will lead to a better basis for carrying out safe anchor handling operations. Proposals include attention zones and suspension criteria. A specification of the rules for stability assessments in relation to large external forces as well as a requirement for calculation of additional dynamic forces will provide the company and master with a simpler and improved basis for safe operation. Further, restrictions to loading conditions have been proposed. In line with the Commission, a requirement for a certificate for net bollard pull for anchor handling is proposed. In order to re-establish the safety factor previously provided by towing hooks with emergency release, new requirements for quick release of load/tension have been proposed. Based on the assessments that have been carried out, it is not proposed to introduce emergency exits from the engine-room through the bottom of the ship. For more accurate assessment and planning, it is proposed to make stability instruments and a separate manual mandatory. The manual shall contain vessel-specific stability information, anchor handling procedure, information about winches and other anchor handling equipment. The procedures should be clearly aimed towards safety management. Anchor handling can be a demanding operation, and in order to ensure that the proposed measures can be instituted, requirements for additional education and training for the master are proposed in the areas of; stability, assessment of forces and safe management of anchor handling operations. After an evaluation of the manoeuvring and effects from the rudders and propellers, education and training in this area is also proposed. For winch operators, a certificate requirement is proposed. Amendments have been proposed for liferafts and EPIRBs so that deployment after capsizing is a criterion in addition to deployment after sinking. Today s possibility to move liferafts to the sides achieve the required capacity is proposed removed. There is also a proposal for increasing the 8

9 number of float-free EPIRBs from one to two, positioned so that the probability is as high as possible that at least one of these will float up to the surface, also in the event of capsizing. Based on a desire to carry out better assessments of safety measures after accidents, proposals have been made to introduce a requirement for S-VDR for certain types of vessels from 300 to 3,000 gross tonnage. Changes to survival suits have not been proposed, but it is recommended that the placement of suits is thoroughly considered, keeping in mind that accidents can progress fast. For work on deck, working clothes with buoyant and insulation properties are recommended. The NMD further recommends that a project for the evaluation of the functional requirements for survival suits is initiated, that investigates, among other things, footwear and dressing time. The areas overlap, familiarisation, identification of the need for qualifications and training are dealt with in the ISM Code. In relation to this, some recommendations have been proposed in addition to the recommendations from the Commission. Safety-critical operations will be given greater attention in the revision of safety management systems. Closer and more frequent audits of recognized organizations that are delegated authority to perform ISM audits are planned. A list of the persons on board all participating vessels is already a requirement for the activity on the Norwegian continental shelf. To internationalize this, proposals have been made for the industry to include it in its guidelines (NWEA) so that the subject becomes a regular item on the agenda at start-up meetings. The recommendations in the report are expected to result in specific proposals for amendments to international and national regulatory systems, and will together with the impact assessments be circulated for consultation. In parallel with the national consultations, proposals that will affect international regulatory systems will be presented to the relevant fora in the IMO and the EU. At the same time a position must be taken on whether to introduce Norwegian special requirements, pending the international processes. In conclusion, it should be noted that the immediate measures of May 2007 with supplements are widely supported internationally. Several foreign authorities have expressed interest in the proposals drawn up in this report. 3 INTRODUCTION The Norwegian Maritime Directorate (NMD) was on 10 April 2008 requested by the Ministry of Trade and Industry to follow-up the report and 9

10 recommendations from the Commission of Inquiry into the loss of the Bourbon Dolphin on 12 April The NMD hereby submits its follow-up report to the Bourbon Dolphin accident. The NMD has had comprehensive meetings with the industry and relevant bodies, including winch manufacturers, ship designers, companies, British authorities and the Norwegian Petroleum Safety Authority. For a complete overview of the NMD s meetings with external parties, see Annex 1. The NMD has in the follow-up work co-operated with Det Norske Veritas (DNV). DNV has worked on an optional class notation for anchor handling vessels. In addition, relevant specialist fora and experts in the Directorate along with ship designers, equipment vendors, companies and the industry have been important contributors in the follow-up process. The NMD has focused on the items that are dealt with in the Commission s report and which the directorate was assigned by the Ministry of Trade and Industry to follow up. The NMD s report, chapters 4 to 11, follows up the Commission s recommendations. The heading of each chapter refers to the items in the Commission s report. A brief introductory description of the matter to be addressed and the recommendation from the Commission is given. Then the regulatory system both at the time of the accident and at the present time is stated. The status at the time of the accident refers to the regulations that applied at the time of the accident. Whether a regulatory system applies to a given ship at a specific time may, however, be dependent on the ship s construction date (date on which keel was laid), as some amendments only apply to new ships, or have a phasing-in period. The NMD s evaluation and recommendation is found at the end of each chapter. In addition to the recommendations from the Commission, proposals for the installation and training in the use of stability instruments are presented in chapter 12. The NMD s follow-up work has been organized in a working group that has been led by Technical Director Lasse Karlsen (Department of Vessels and Seafarers). The group also consisted of Bodil Pedersen, Mona Kristensen, Ole Morten Fureli (Section of Cargo Vessels), Torgeir Bjørntvedt (Section of Passenger Vessels), Ian C. Burman (Section of Legislation and Contracts), Bjørn Vik Mjeltebakk (Department of Inspection), Per Jostein Breivik, Per Morten Tennøy (Station Ålesund) and Arne Bakkevig (Department of Strategic Safety). 3.1 Terms of reference On 15 December 2007 the Director General of Navigation and Shipping appointed an internal working group in the NMD responsible for following up the matters that were emphasized in the consultations and the follow-up 10

11 work after the Bourbon Dolphin accident. The working group also had to follow up other relevant matters that may provide lessons learned from the accident. In the letter of 10 April 2008, the NMD was assigned by the Ministry of Trade to follow-up the report from the Commission of Inquiry into the loss of the Bourbon Dolphin. The Director General of Navigation and Shipping extended the existing terms of reference for the working group to the follow-up of the Commission s report and the recommendations that affect the NMD. 11

12 3.2 More on the measures The accident has revealed a lack of adherence to: Compliance with legislation and guidelines, including preparation of and compliance with plans and procedures Specific requirements for anchor handling vessels Supervision and revision of safety management This applies both at operator level, rig and vessel. As also pointed out by the Commission, it is not a lack of regulations and procedures, but compliance with such that characterize the accident. This creates challenges for the authorities when it comes to preventing similar accidents from happening in the future and learning from the experiences in order to contribute to the improvement of safety management in general. It is not desirable or appropriate to make the regulations too detailed, as this leads to a strong focus on single provisions in the rules rather than assessing overall safety. Detailed rules have limitations to allow for any changes in technology or needs as these are evolving continuously. This, combined with an industry where complex solutions are constantly being developed, often makes the industry itself best placed to assess which specific measures that must be implemented to maintain the desired level of safety. To achieve this, however, the competence that exists in objective-based and function-based regulatory systems, and the industry s own guidelines and procedures, must provide the basis for the industry s daily activities. This applies at all levels, also in the design phase, so that compromises in operational flexibility do not affect safety. The company s responsibility for this is laid down in the Construction Regulations and requirements for safety management. The NMD primarily regulates vessels and units operating under the Norwegian flag. In the accident in question, two of the anchor handling vessels were Norwegian. However, in order to get a broader picture, the accident is assessed as if it occurred on the Norwegian continental shelf. There is a generally good appreciation of risk in the industry. Plans and procedures for the rig move in question contained relevant information, but lacked safety assessments for the anchor handling vessels. Also, plans and procedures are not always complied with. It has been proposed to the NMD to consider requirements for the testing of people who are responsible for demanding assignments, such as mooring operations. Such evaluations are not unusual for certain positions. 12

13 To achieve a proactive safety management, consecutive and systematic risk assessments are required to identify the need for improvements. It is therefore unfortunate that the assessments and actions made are largely based on previous problems and accidents, while potential risks are not assessed as thoroughly. This despite significant changes to the design of the vessels, as well as of the extent, forces and natural conditions on the assignments being carried out. In evaluating the measures and how these should be implemented, the balance between technical criteria, training and requirements for the person in charge of the operation has been emphasized. Safety management requires commitment, time and resources from all involved. 3.3 More on the Ship Safety and Security Act LEGAL FRAMEWOK AT THE TIME OF THE ACCIDENT The Seaworthiness Act, with supplementary regulations, was the basis for the public control of the shipping in Norway in the last century. Pursuant to this Act, the responsibility for compliance with provisions contained in Norwegian statutes to ensure the seaworthiness of ships and protect the interests of those on board rested with the shipmaster. The responsibility of the owner included the establishment of routines with regard to the safe operation of the ship. Furthermore, the shipowner should not cause or participate in causing an unseaworthy ship to proceed to sea or to be employed contrary to the official permits issued for operation of the ship. AMENDMENTS TO THE STATUTORY FRAMEWORK NEW SHIP SAFETY AND SECURITY ACT The Ship Safety and Security Act, which entered into force on 1 July 2007, has replaced the Seaworthiness Act. The structure of the new Act provides a better overview of the contents of the Act. The main responsibility now rests with the company, and not with the master. This Act also provides the NMD with greater flexibility and more response options during their supervisory work. The requirements given in the Seaworthiness Act are largely continued in the new Act and its appurtenant regulations. The old Act contained several detailed provisions, while the new Act leaves the details to the regulations that are issued pursuant to the Act. The contents of today s technical regulations have not been amended, seen as in relation to the rules that applied under the Seaworthiness Act. The development of the regulations will take place continuously depending on requirements. The greatest change in relation to the new Act has been the shift of responsibility from the master to the company, though the master and other persons working on board must participate. This means that it is the responsibility of the company, and partly the master, to ensure that the 13

14 regulatory system is complied with. The NMD has a general responsibility for supervising the safety management system and ensuring that other conditions prescribed in the Act are fulfilled. The Directorate has several tools at its disposal to supervise the ships, including random inspections. This work can also be delegated to others, e.g. classification societies. The Ship Safety and Security Act has also provided the NMD with a new system of sanctions with more sanction mechanisms than before. Some of these mechanisms are coercive fines, violation fines and measures against the vessel, in addition to other penalties and imprisonment. 3.4 The Commission s comments to the NMD The Commission criticises the NMD in its report, see the Commission s report chapter p. 57 and chapter 12 p. 129: The vessel s stability book contains a chapter called Instructions for Master. The contents of this chapter are standardised and provide no direct information about important matters related to the vessel s stability in various operations. This is an unfortunate practice that the Norwegian Maritime Directorate ought to have pointed out during its approval of the stability book. It also merits criticism that DNV had not in previous audits pointed out the failure to prepare a procedure for anchor handling, since the ISM Code demands a procedure for key operations. This criticism is also directed against the Norwegian Maritime Directorate, which audits DNV. Questions may also be raised as to whether the non-conformances were so serious that the Bourbon Dolphin ought not to have been issued with a safety management certificate following the DNV audit. The NMD notes the commentaries from the Commission and other information in the report. The following measures are implemented and will be given priority in future follow-up and supervisory work: The follow-up of the stability information has already been improved in accordance with the immediate measures. However, in this report, amendments and improvements have been proposed in Chapter 4 concerning stability. Regular meetings med classification societies to quality assure the ISM audits they perform on behalf of the NMD. Systematic, supervisory monitoring of the classification societies by performing observations, unscheduled surveys, vertical audits and system audits, with regard to the approval of newbuildings and follow-up in the operation phase. Increased focus, when reviewing the documentation, whether the ships are suited for the assignments they are planned to be used for. 14

15 Increased focus on controlling that the ship s procedures are ship-specific where required, and that all necessary details and factors are considered in relation to the vessel s function and area of operation. Evaluation of the qualification requirements for ISM auditors. Increased focus on training, overlap and familiarisation, including examination of crews that can be documented and re-examined. 3.5 Follow-up of recommendations from the Commission Chapters 4-11 deal with the NMD s follow-up of the Commission s recommendations and contain proposals for measures. 4 STABILITY OF ANCHOR HANDLING VESSELS (13.3) 4.1 Stability calculations (13.3.1) Problem as described in the Commission s report (Cf p ) The Bourbon Dolphin was a combined PSV and AHT vessel, also described as an AHTS. Designing a combination vessel is more demanding than designing a PSV or an AHT. The main focus for a PSV is cargo capacity, whereas for an AHT there is more focus on propulsion system and deck layout. Factors affecting stability are directly affected by the compromise resulting from different needs. Important factors for an AHT in this context are: Overall dimensions Buoyancy configuration, including design of hull and superstructure on deck Weight and centre of gravity The winch s pulling-power Capacity for leading of wire Bollard pull Ballast capacity The vessels are as a rule designed with a large beam in relation to their depth, so that they have little or no buoyancy over the deck aft of the superstructure forward. Developed stability requirements have been developed for this type of vessel (IMO Resolution A.469 (XII)), which means that in order to have sufficient stability in various load conditions, particularly with large draught and little freeboard, there will be a need for a high GM. For most load conditions a high GM yields disadvantageous sailing characteristics in relation to rolling. It is therefore normal for these vessels to have one or more roll reduction tanks in order to enhance comfort on 15

16 board. Use of roll reduction tanks helps to reduce the vessels static stability and can thus, for certain vessels in given operations, constitute a safety hazard. In the light of the above, an AHTS vessel can be more demanding to operate in relation to stability. This is a challenge for the crews. It may therefore be more demanding to plan and control load conditions for these vessels than for others. The Commission considers that in consequence of this there ought to be particular attention paid to the stability of these vessels, both in relation to scope and content of aids (stability book, load calculator [stability instruments]) and qualification/training of crews Recommendation from the Commission (Cf p ) In order to create robust safety barriers during anchor-handling operations, including making sure that bollard pull and winch pulling power for AH vessels at the design stage are chosen dependently of the stability criteria, the Commission would make the following proposals: Preparation of rule conditions for anchor-handling: - All conditions shall be prepared with 10 and 100% bunkers. - All winches shall be full of the heaviest possible line type. - External force with following characteristics: 1. Vertical load: - In vertical load, the full winch capacity shall be used between the outer towing-pins. The winches have full pulling power in the first layer. The requirement that the weight of the wire shall at the same time be set equivalent to full drums is justified by the fact that an extra margin is desirable. List arm shall be calculated from the centre of the vessel to the outer edge of the roller and with vertical point of attack in the upper edge of the stern roller. During this vertical load, the vessel shall have a maximum list angle corresponding to a GZ value equal to 50% of max GZ. 2. Run-out of chain: - In running-out of chain a maximum force from the mooring line shall be calculated. The maximum force shall have its basis in both static and dynamic loads. This force shall be decomposed into a vertical force and a horizontal force in the vessel s transverse direction. The list arm for the horizontal component shall be calculated from the height of the working deck at the towing-pins to the centre of the propulsion propeller, or the aft lateral propeller if this is deeper. The heeling arm of the vertical 16

17 component shall be calculated from the centre of the vessel to the outer edge of the stern roller and with vertical point of attack in the upper edge of the stern roller. The mooring line shall have an angle of attack of minimum 25 in relation to the vessel s longitudinal axis in the horizontal plane. The angle in relation to the vertical plane shall be set as the one that gives the biggest list angle for the vessel. If the force from the mooring line is less than the maximum bollard pull, the angle shall be set at 90º. Under the influence of forces from the mooring line, the vessel shall at maximum have a list angle that corresponds to a GZ value equal to 50% of max GZ. The maximum manageable force from mooring lines that emerges these calculations will be the vessel s capacity for this type of operation. - If it is necessary to ballast the conditions to achieve a given manageable force, the ballast used shall form the basis for ballast instructions dedicated to anchor-handling. KG-limit curves Specific KG-limit curves shall be prepared for anchor-handling operations that introduce two new criteria (in addition to existing requirements for supply ships). A static moment shall be used, related to the vessel s maximum vertical load during operation of the winch. List arm shall be calculated as shown above. Under the influence of this moment, the vessel shall at a maximum develop a list angle that corresponds to a GZ value equal to 50% of max GZ. Under the influence of the maximum manageable force from the mooring line, a curve for list moment shall be calculated. List arms for the vertical and horizontal component shall be calculated as shown above. Under the influence of this moment, the vessel shall at a maximum develop a list angle that corresponds to a GZ value equal to 50% of max GZ. The proposed requirements for stability will mean that the shark-jaws can be used under all stability conditions in the whole area between the outer towing-pins Status of the regulatory system AT THE TIME OF THE ACCIDENT The Construction Regulations contain general requirements for intact stability as well as requirements for intact stability allowing for the transverse forces for ships engaged in towing. Equivalent additional requirements for intact stability for ships engaged in anchor handling have not been prepared. The main requirements of IMO Res. A.469(XII) Guidelines for the design and construction of offshore supply vessels, are incorporated in the Construction Regulations. These guidelines were amended by IMO Res. MSC.235(82) on 1 December However, national law was not amended as a consequence of this. 17

18 TODAY No amendments at national level, but the current Circular No on immediate measures provides guidelines for anchor handling The NMD s evaluation The NMD s work is based on the Commission s proposed solution. Questions regarding requirements for built-in and operational stability requirements have been subject to discussions with classification societies, shipyards, ship designers, companies and crew on this type of vessel. Moreover, test calculations have been carried out on a range of existing designs to show how capacity is affected when new stability requirements are introduced. These stability calculations have been done by naval architects on their own designs for the NMD, but DNV has also run calculations on selected vessels to map the consequences of stability requirement amendments. The test calculations, cf. Annex 2, indicate that the vessel s maximum pull varies according to variations in the quantity of wire and the type of winch, the compressive force on the stern roller and the amount and distribution of tank content in general The NMD s recommendation After an overall assessment of the limits that should be placed on the design and operational stability of anchor handling vessels, the NMD will propose specific stability requirements. Traditionally, the dynamic aspects of increased limit values have been added to the criteria when preparing stability criteria. The NMD has nevertheless decided to use the Commission s proposal to include dynamic effects in the mooring line force. This will result in an increase in the total forces that must be considered on a vessel during anchor handling, and thus a reduction in the vessel s capacity STABILITY CRITERIA: The criterion proposed by the Commission of Inquiry was one of the three criteria recommended by the NMD in the immediate measures. The criteria in these recommendations will be used in the new regulations: The list angle as a result of inflicted moments shall not exceed: 15 : This angle is low enough to enable corrective action to be taken and make suspension of operation possible, at the same time as the angle is so large that it clearly indicates that the load is too high. angle for water on deck: A freeboard requirement that makes work on deck possible in a critical static situation, at the same time as the ship s stability is significantly reduced beyond this 18

19 angle. Angle for 50% of GZ max : Provides a safety barrier with regard to the righting arm. The Commission s recommendations mean that vessels will have a certain level of stability in reserve when tension from the mooring line is taken into account. This level is apparent from the criterion stating that the maximum righting arm (GZ) shall not be reduced with more than 50% after tension is imposed on the vessel. The test calculations that were carried out indicate that the stability reserve can be relatively little when a vessel is loaded in such a way that the general requirements for stability are satisfied with small margin. To ensure that an acceptable level of stability reserve exists in all loading conditions, it is necessary to introduce a minimum level of stability to provide this reserve. A minimum level of stability will be able to preserve the stability of the vessel when unpredictable variations in the forces acting on the vessel occur during an operation, such as waves, wind, current and tension in the mooring line. The NMD proposes an area requirement of mrad between heeling arm and righting arm up to the second intersection point, angle of flooding or 40. The area requirement is based on the IACS area requirement for towing vessels, which is 0.09 mrad, adjusted for a dynamic increase of 40%. The area requirement is expected to contribute to a greater extension of the GZ curve. Anchor handling vessels shall comply with the current towing requirements in relation to their maximum bollard pull LOADING CONDITIONS: Typical anchor handling vessels are often multifunctional vessels, with an option for the delivery of both fuel oil and freshwater to offshore petroleum installations. They are likely to have oversized fuel oil and freshwater tanks. These variables, along with the ship s ballast capacity, will then have a relatively large impact on the ship s capacity. In order to prepare simple and clear instructions to the ship s crew for the conditions related to the ship s capacity, limitations in the use of roll reduction tanks and necessary ballasting, a stated consumption sequence must be assumed. The NMD therefore proposes that an emptying sequence of the consumption tanks from maximum capacity to empty vessel shall be determined for each vessel. 19

20 Based on this consumption plan, departure and arrival conditions shall be prepared, with respectively 100% and 10% fuel oil and freshwater, and the worst intermediate situation(s) shall be prepared. The other situations shall include a given deck cargo and at least one roll reduction tank with operational filling. When it comes to load on the winches in the different conditions, the NMD will propose to introduce a requirement for 33%, 67% and 100% load on all winches. This is to illustrate a reduction in the ship s capacity as a result of increased load on the winches. The effect of flooding of open chain lockers shall be illustrated with regard to impact on the vessel s capacity, although not to be decisive for the resulting capacity. This is because the potential for flooding during the operational conditions, including wave conditions, is not considered to be greater than can be addressed through drainage via the tank s associated bilge arrangements. Moreover, openings in the deck shall be equipped with frames as high as practically possible, however not less than 600 mm, loose or fixed, depending on the arrangement. Conditions and assumptions for consumption plans shall be presented to and approved by the owner. The stability documentation, in its entirety, is proposed subjected to control by the NMD prior to the issue of certificate HEELING MOMENT: The NMD will continue the Commission s recommendation for moment arms, but suggests that the upper outer edge of the stern roller is used in the calculation of both moment arms. On the basis of standard arrangements with towing pins and stern rollers, a moment arm greater than the distance from centerline to the outer edge of the stern roller is not considered necessary. Arrangements controlling the wire and chain within a narrower area may result in other and reduced moment arms. In any case, this must be subject to special evaluation in the design phase ANGLE VARIATIONS FOR THE TENSION: The NMD will continue the decomposition angles the Commission has chosen, i.e. an angle (here defined as α) between the ship s centerline and the anchor line in the horizontal plane, and an angle (defined β) between the horizontal plane and the mooring line through the point of attack. This is because both of these, for instance in connection with the running-out of chain, can be determined by means of the navigational aids found on board an anchor handling vessel. The angle α will be given as the angle between the line from the line s defined point of attack on the vessel to the point where the line leaves the rig and the vessel s heading. The angle β will be given based on the following variables: 20

21 the distance from the line s point of attack on the vessel and the point where the line leaves the rig, the run-out line s composition and the length of the run-out chain These three variables can be controlled in such a way that the angle β can be determined TABLES/CURVES FOR MAXIMUM PERMISSIBLE MOMENT: Curves shall be prepared so that the master can easily determine the maximum forces that can be applied to the vessel, as a function of displacement/draught and vertical centre of gravity (VCG) so that the stability criteria are satisfied. In it is assumed that the dynamic additional forces are calculated and clearly presented in the anchor handling plans, so that the value in question can directly be compared to calculated/observed maximum permissible tension. The limit curves should be given as curves exceeding the maximum permissible moment, as this would allow the use of the same curves for the whole range of the anchor handling operations the vessel is going to perform. The various anchor handling operations, such as pulling the anchor or running-out of chain, could be described by different variations of the angles α and β. When it comes to pulling an anchor when the vessel is positioned straight above the anchor s position at the bottom, α will probably be small and β be close to 90. For running-out of mooring line β will vary, while α already after the manoeuvring of the vessel can be kept small. The maximum permissible moment can, by using the selected angle intervals, be calculated back to a maximum tension, which will appear as the minimum pulling power in the intervals DYNAMIC LOADS: Under the operational requirements the NMD has proposed that the master, through regulatory amendments, should have the responsibility to ensure that dynamic loads on the vessel are taken into account during an anchor handling operation. The master ensures that the maximum tensions shown in the anchor handling plans take account of the dynamic additional forces that may occur within the stated window of operation for waves, wind and current. If such information is missing, and on the basis of the Commission s approximation value of 1.4, a preliminary reduction value of 29% of the maximum permissible static tension is proposed. There is currently software for the calculation of dynamic additional forces, which can be used. The NMD will nevertheless take the initiative to have the dynamic effects in connection with line tension on anchor handling vessels 21

22 further discussed, and prepare proposals for common international guidelines for the assessment of dynamic forces EFFECT OF STERN FORCES ON THE SHIP S TRIM AND DISPLACEMENT: In preparing the loading conditions, the effect of stern forces on trim and displacement shall be taken into account by considering the pressure by a concentrated load in the ship s centerline in the upper edge of the stern roller. The size of the concentrated load may be set as a conservative value. Alternatively, more accurate and iterative methods for the stipulation of the stern force may be used. The NMD will consider initiating test calculations in order to examine whether the effect of free trim regardless of axis has a significant impact on certain types of vessels SUSPENSION CRITERIA: The two above-mentioned angles α and β will in practice be suspension criteria, considering that they are part of input values in the crew s calculations of the ship s available capacity in a given loading condition. The angles must be chosen in order to calculate the maximum permissible tension on the basis of the proposed tables/curves for maximum permissible heeling moment. The maximum tension is therefore only valid within the indicated angles. If the displayed tension exceeds the calculated maximum permissible tension, the operation must be corrected or suspended. The operation must also be corrected or suspended if the external forces that are used for the calculation of the dynamic additions in the anchor handling plan are exceeded CONCLUSIONS: On the basis of the proposed loading conditions, which cover varying levels of fuel oil and freshwater, in combination with a range of loads on all winches and limit curves, the NMD is of the opinion that general requirements for stability may be achieved, which will make it easier to assess whether the vessel has the capacity to perform a given job. However, in order to assess the assignments the ship is to be used for, the company must be familiarized with the vessel s characteristics before it is put into operation. 4.2 Stability booklet (13.3.2) Problem as described in the Commission s report (cf p. 57) Instructions for Master. The contents of this chapter are standardised and provide no direct information about important matters related to the vessel s stability in various operations. 22

23 The company had not prepared instructions for use of the roll reduction tanks as required by the Building Regulations Section 15. It was thereby not communicated that the tanks of the Bourbon Dolphin ought to be empty during anchorhandling operations. Load conditions for anchor-handling do not follow the standard for set-up of conditions that the shipyard had used for other vessels. Use of winch power and appurtenant point of attack for this (against the inner towing-pin) is not compatible with the vessel s maximum winch power and the use of the shark-jaw. (cf p. 128) It is not documented that the vessel s stability characteristics were such that the equipment could be used at its full capacity. The restrictions were not communicated directly and clearly in the stability book or in any other way to those who were to operate the vessel Recommendation from the Commission (Cf p. 138) The stability book must contain a supplement of calculations in line with the recommendations described above, subject to the approval of the authorities. Under the current regulatory system, it is a requirement that the stability book contain instructions that in a rapid and simple manner enable the master of the vessel to enjoy precise guidance about the ship s trim and stability under different sailing conditions. The Commission has the impression that these instructions have been standardised and consequently fail to communicate vessel-specific factors. A vessel-specific content would make it easier to safeguard stability on board. The following shall be dealt with in the instructions: concrete operational restrictions, capacities for given operations, and other operational factors of significance for the vessel s stability. Operational restrictions may for example include the use of roll reduction tanks and ballast tanks in various operations. Capacities for given operations may for example include maximum manageable force from the mooring line during running-out and maximum capacity for carriage of deck cargo. Other factors may for example include the need, during any unusual use of the winch, for special attention related to stability, demanding that stability factors be studied more closely Status of the regulatory system 23

24 AT THE TIME OF THE ACCIDENT The term stability booklet is not used in the NMD Regulations, but there are requirements for the information that is normally presented in the stability booklet. According to the Construction Regulations stability information shall be prepared to enable the shipmaster by rapid and simple processes to obtain accurate guidance as to the ship s trim and stability under varying conditions of service. The Safety Measures Regulations contain provisions concerning stability data and aids for controlling the stability which shall be kept on board. Furthermore, there are provisions in the Regulations concerning what should be taken into account or provided for during normal operation. SOLAS contained provisions about stability information in Reg. II-1/22 and Reg. II-1/25.8 that also applied to Norwegian ships TODAY Some amendments have been made to SOLAS with respect to the contents of the stability information the master shall have. The amendments are found in the new Regulation II-1/5-1 in SOLAS which are quoted in Res. MSC.216(82). Current Circular No on immediate measures provides guidelines for anchor handling operations The NMD s evaluation The NMD shares the Commission s opinion of how the form and contents of the stability booklet should be. The NMD now requests that vessel-specific instructions be submitted prior to approval and that instructions for the use of roll reduction tanks are prepared. The NMD has found that there is a lack of information from designers and consultants when describing limitations and capacity reductions in individual designs and vessels. This can to some extent be related to the formulation of the regulations regarding how stability information should be drawn up and what information to include here. However, the responsibility for ensuring that information on the vessel s stability is available, in relation to the relevant load, lies with the shipping company The NMD s recommendation The NMD recommends that, through regulatory amendments, the minimum requirements for the stability manual for anchor handling vessels is stated. The usability and availability of critical information must be emphasized. 24

25 The NMD will further recommend requirements that the master shall have tools and numerical examples available for the calculation of the vessel s stability. This information shall, as a minimum, include: An overview of the most favourable consumption sequence for fuel oil and freshwater, with its recommended use of ballast water. Instructions for the use of roll reduction tanks that clearly convey what stability-related consequences the use of such tanks have. A description of how the ship s trim, draught and vertical centre of gravity for a given loading condition is determined, as well as the formulas required to determine the maximum permissible tension from the maximum permissible heeling moment. A numerical example that shows how the maximum permissible tension is determined for a given loading condition for a selected set of the angles α and β. Vessel-specific instructions based on the consumption plan, which, among other things, shall be linked to the operational limitations as described under 4.1, described in an accessible way in the stability booklet. However, the stability information is extensive, and it is therefore proposed that separate manuals are prepared for special operations. An anchor handling manual will naturally contain information related to any particular operational conditions, including stability, risk assessments and specific operational procedures. Information on winches and other anchor handling equipment should be in the same manual. 4.3 Training/operation (13.3.3) Problem to be addressed and recommendation from the Commission (Cf p. 138) Use of simulator training is a positive measure for raising the level of expertise, and is encouraged in the training of personnel. The very best thing would be for simulators to be vessel-specific. Simulator training should include variations in the forces that the vessel must be expected to handle and provide relevant feedback to the operator about the consequences. The Commission would recommend to maritime educational institutions that they review existing training activities in stability with a view to these also addressing factors related to towing and anchor-handling operations. It is also recommended that companies and the maritime milieu establish a stronger focus on maintenance of operational stability on board Status of the regulatory system 25

26 AT THE TIME OF THE ACCIDENT The Qualification Regulations implement the STCW Convention, which contains requirements for the education which is a basis for the issue of certificates. The stability training here is general and does not deal with specific problems associated with anchor handling. Further, the STCW Code sets out requirements for manoeuvring. The officer of the watch of ships of 500 gross tonnage and upwards shall have knowledge about the consequences of wind and current. In accordance with the STCW Code, masters and chief officers shall be capable of manoeuvring and handling a ship under all conditions, this includes using the propulsion machinery and manoeuvring systems, handling the ship in poor weather, under towing operations, be able to determine the characteristics of the manoeuvring and propulsion machinery for common types of ships with special reference to the stopping distance and turning radius at various draughts and speeds. Generally, the vessel s safety management system shall help ensure that the crew receives adequate training, cf. the ISM Code TODAY When it comes to training related to specific types of vessels, reference may, after the entry into force of the Ship Safety and Security Act, be given to the general provisions relating to qualifications The NMD s evaluation PROBLEMS RELATED TO MANOEUVRING When manoeuvring a vessel engaged in towing or connected to an anchor chain, the crew must pay due regard to special conditions related to manoeuvring. A vessel that has speed through the water is steered by the stern, which means that a port turn is done by placing the rudders over to the port side so that when the water hits the rudders the stern is pushed to starboard. When the stern moves towards the starboard side, the vessel s direction is changed to port resulting in a turn to port. The same principle will apply to vessels which manoeuvre without a rudder, e.g. an azipod propeller. In an operation in which the vessel does not move forward or moves slowly forward, the vessel can be manoeuvred sideways by using the side thrusters. When the traditional main propellers are run at the maximum, and the vessel still does not accellerate through the water as a result of that it is held back by an inertia and water resistance force, the pushing force from the side thrusters will decline significantly due to water suction caused by the main propellers. 26

27 For traditional main propellers the greatest lateral force is therefore achieved by using propulsion propellers in combination with the vessel s rudder, see figure 1. FIGURE 1 EFFECTIVE SIDEWAYS MOVEMENT AT LITTLE OR NO FORWARD SPEED In order to achieve a lateral movement towards port from the propulsion propeller, the rudders, alternatively the azipod, must be rotated towards starboard, as for example in a starboard turn. This must be done because a starboard turn will cause propeller water to push the vessel s stern heavily towards the port side. This lateral force is considerable and can normally be considered to be approximately 60% of the vessel s bollard pull for traditional propeller systems. Accordingly it is not very efficient to use the lateral thrusters when the main propellers are being used at near maximum effect. All available engine power should be used on the main propellers. If the rudders are placed towards the port side during towing when a port turn is desired, the ship must be able to move the stern in a certain speed 27

28 and distance. This method is for instance applied when towing a trawl. Rudder deflection to the port side will, as mentioned above, attempt to push the stern towards the port side. If the stern of the vessel is prevented from moving or moves very slowly due to an external force, radial thrust force is all that is obtained. If a vessel is further prevented form turning to port because of a towing fastening point astern of the propellers, the thrust force will actually be able to push the vessel to starboard, see figure 2. FIGURE 2 UNFAVOURABLE SIDEWAYS MANOEUVRING AT LITTLE OR NO FORWARD SPEED In the case of the Bourbon Dolphin, the problem of getting the vessel to change heading to port was identified in part through the action that was done to move the chain from the starboard towing pin to the port towing pin. Thus, it is conceivable that the manoeuvring of the rudders and main propellers largely contributed to reducing the vessel s force and movement to port and that the drift to starboard could not be counteracted PROBLEM RELATED TO STABILITY 28

29 Anchor handling in the form used for the anchoring of rigs and other special vessels like pipelaying barges and production ships is a relatively new activity that has progressed rapidly from the 1960s to the present. From only towing the rig s own mooring line via the centric towing pin, operations in deeper waters and stricter requirements for mooring have led to a significant change in the vessels capacity, especially for lifting, see figure 3. Splicing of the mooring lines to insert alternative links or to increase the length beyond the capacity of the rig s anchor winches, has further led to, among other things, double towing pin sets which separately are positioned somewhat to the side of the vessel s centre. Thus, all vertical loads from the mooring line of the towing pin sets produce a heeling moment. FIGURE 3 THE PROGRESSION OF ANCHOR HANDLING VESSELS Anchor handling, which is a combination of lifting and towing, is performed by vessels which, in terms of stability, are constructed as supply vessels. Such vessels are permitted to have their maximum righting arm (GZ max ) at 15 of list. For regular cargo ships it is recommended that the righting arm should not reach its maximum until after 30. However, the requirement is that the area before the peak point should increase from mrad at 30 to 0.07 mrad at 15. The possibility of placing the GZ max down towards 15 provides operational advantages, but also disadvantages that may jeopardize the safety. Anchor handling vessels with a GZ max of 15 are perceived as very rigid and hence stable since they, for example, will only list to approx. 5-6 at 50% of the maximum righting arm, while a merchant vessel with a GZ max of 30 will list to In practice a 5-6 list will not be experienced as dangerous, while a list will be perceived as dramatic. 29